Generating bifunctional fusion enzymes composed of heat-active endoglucanase (Cel5A) and endoxylanase (XylT)
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Bifunctional enzyme constructs were generated comprising two genes encoding heat-active endoglucanase (cel5A) and endoxylanase (xylT). The fused proteins Cel5A–XylT and XylT–Cel5A were active on both β-glucan and beechwood xylan. An improvement in endoglucanase and endoxylanase catalytic activities was observed. The specific activity of the fusion towards xylan was significantly raised when compared to XylT. The fusion constructs were active from 40 to 100 °C for endoglucanase and from 40 to 90 °C for endoxylanase, but the temperature optima were lowered from 90 to 80 °C for the endoglucanase and from 80 to 70 °C for the endoxylanase. XylT in the construct XylT–Cel5A was less stable at higher temperatures compared to Cel5A–XylT. Due to the enzymatic performance, these fusion enzymes are attractive candidates for applications in biorefineries based on plant waste.
KeywordsBifunctional Cellulase End-to-end gene fusion Extremophiles Thermozymes Xylanase
MR received a scholarship from the KAAD (Katholischer Akademischer Austauschdienst). The authors thank Yang Li for the help with some experiments.
Supplementary Table 1—Oligonucleotides used in this study
Supplementary Table 2— Purification of recombinant Cel5A-XylT and measurement of its activity towards β-Glucan and beechwood xylan
Supplementary Table 3—Purification of recombinant XylT-Cel5A and its activity towards β-Glucan and beechwood xylan
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